E.g.f.: exp(exp(x) - 1) / (sec(x) + tan(x)).

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =4a(5) =-4a(6) =31a(7) =-144a(8) =379a(9) =-5560a(10) =8572a(11) =-263128a(12) =473485a(13) =-15744416a(14) =47003477a(15) =-1206879556a(16) =5944492012a(17) =-119190424496a(18) =876847239971